Design of novel edible hydrocolloids by structural interplays between wheat gluten proteins and soy protein isolates

Wheat gluten proteins (WPs) are nutritious protein with a large yield, but they are rarely industrially attractive due to their poor water solubility. In this experiment, a pH-cycle was used by co-dissolving WPs and soy protein isolates (SPIs) with WP/SPI ratios (W/S) from 1:0.1 to 1:2 at pH 12, and further readjusting the pH to neutral, which improved the water solubility of WPs from 4.5% to 72.4% while maintaining the intact primary structure of proteins. The morphological analysis, fluorescence and far-UV spectra illustrated that the WPs interacted with SPIs to form combined particulate architectures by the co-folding of proteins during neutralization. The combined structures are significantly resistant to renaturation due to the unfolded protein backbones with high structural tenacity. The more charged surface provided complexed proteins with greater affinity to water molecules and protected the protein molecules from aggregation. Moreover, the amino acid compositions closely met the amino acid requirements for adults. The results indicate that the protein complexation induced by adjusting the pH may be a facile and applicative approach to modify insoluble proteins into edible hydrocolloids, and has great potential for enhancing nutritional values of proteins.